Control mechanism for variable volume compressors



March 17, 1936. w. w. SCHROEDER 2,034,272

CONTROL MECHANISM FOR VARIABLE VOLUME COMPRESSORS Filed Aug. 7. 1930 w. w. Scunpzusm.

INVENTOR A 'ORNEY Patented Mar. 11, 193 D 2,034,272

UNITED STATES, PATENT OFFICE CONTROL LIECHANISM FOB VARIABLE VOLUME COMPRESSOBS Walter W. Schroeder, Newark, N. 3., assignor to Worthington Pump and Machinery Corporation, New York, N. Y., a corporation of Virginia Application August '7, 1930, Serial No. 473,687 TClaims- (cl. 137-139) This invention relates to fluid compressors embe first described in connection with the acployed for compressing air, gas or analogous companying drawing, showing a control mechfluids and more particularly to a novel apparatus anism for variable volume compressors 'of the for regulating the unloading and loading of compreferred form embodying the invention, and the pressors gradually; that is, an automatic presfeatures forming the invention will be specifically 5 sure regulator by means of which, the volume of. pointed out in the claims. fluid compressed is varied automatically with the Fig. l is a diagrammatic view partly in section demand for fluid so as to maintain practically showing the improved control or regulator mechconstant pressure and obtain the resultant adanismfor variable volume compressors.

vantages in compressor operation. Fig. 2 is a fragmentary view in section through 10 Among such advantages are relatively low tema switch structure embodied in'the control or peratures, resulting in relatively high efliciencies, regulator apparatus. reduced carbon deposits with the resulting im- Referring more particularly to the drawing, a proved valve action, improved lubrication and double acting air or gas compressor is shown,

consequently less cylinder wear. These features which o p s the cy d 1 in which the 15 are particularly marked should the compressor ton 2 reciprocates. T pp ends of the W operate at low capacity and appreciably part of inder, namely the head and crank ends 3 and l the time, .such as most compressors are called espec v y, h pp types of inlet Valves upon to do. associated therewith for controlling the inlet of In variable capacity compressors embodying fluid into the cylinder l and as is usual in the 20 the'present invention, a series of control valves construction of this type, clearance pockets 6 are employed, each acting to control a partial and l are provided for permitting variationof unloading of the compressor cylinder or cylthe volume of pressure fluid delivered by the inders, for varying the cylinder capacity in aco p es cordance with the movement of control valves In 1 o t e d w 9- Dertielller wenge- 25 Operated and the required operation of these ment of the clearance pockets is shown 'but it is control valves is secured by a regulator, acting to be understood that the present invention is ,to vary the relative pressures tending to move not t d r use W Comp s embodying these valves in opposite directions for loading this Particular yp of clearance and yp or unloading the cylinders. arrangement but that it may be employed in 3 An Object of the present invention is to proconnection with any of the improved compressor vide a regulator or governor mecha i for structures embodying various clearances and bycontrolling operation of said control valves, which p s arrangements for P v d the Volume 0011- is comparatively simple in construction, positive trol desiredin operation and will eliminate any indecisive or In the construction illustrated in 1 0f the 35 hunting action and reversing movement during drawing, the Clearance chamber 7 has 60111- any individual operation in case of pressure varimunieetien through an Opening 8 With the Crank ation before the individual operation is comnd 3 of the compressor cylinder, wh the a pleted. ance chamber 6 has communication through an 40 More specifically, the present invention com- Opening 9 with the ad d 4 0f t y d r 40 prises a, pressure fluid distributor, whi h 11 The two clearance chambers 6 and 'l have comtributes the operating pressure fluid to the conmunieetien W each Other through an Opening trol valve and which is operated in step by step ll t p v de a bypassing arrange e 0P- sequence by electrical means such as a solenoid erating the Compressor at Zero eepaeity- 46 or solenoids, the energizing of which is com All of the openings 8, 9 and lo are controlled trolled by means responsive to pressure in the by control valve structures H, l2 and (3, all of receiver in which the compressor discharges or which are alike in construction, comprising the by means responsive to predetermined pressures valve discs l4, and the stems l5 which are con- ,to control the capacity of the compressor in acnected topiston IS. The pistons l6 are mounted 50 cordance with the demand for the fluid under for reciprocatory movement in the cylinders ll 50 pressure discharged by the compressor. and the valve discs M are held seated by the With these and other objects in view, as may springs l8 and pressure against the outer sides appear from the accompanying, specification, the or faces of the pistons I6. invention consists oi various features of con- The unseating oi the various valve discs [4 of struction and combination of parts, which will the valves H, l2 and I3 is controlled by the 55 regulator embodying the present invention through the medium of a distributor valve structure 20.

The distributor valve 20 includes a reciprocatory valve piston 2|, the reciprocation of which indirectly controls the operation of the unloading or loading control valves in the manner hereinafter described and this distributing valve piston 2| is in turn controlled in its operation by variation in the receiver pressure through the medium of the regulator mechanism embodying the present invention.

The improved regulator mechanism comprises a solenoid or solenoids 58, which may be a single solenoid embodying a plurality of individual coils as shown in the drawing or it may be individual solenoids as desired. However, the single solenoid embodying a plurality of individual coils tends toward simplicity in construction and it is so shown in the drawing and will be described herein as such type of solenoid.

The core 5| of the solenoid 5|l'is connected to the valve stem 52, which is in turn connected to the valve piston 2|. The valve piston 2| is moved in step by step sequence either to the right or to the left, depending upon the energizing of the various coils 53, 54, 55, 56, or 51 of the solenoid 50.

A switch 58 is provided for controlling the energizing of the various coils of the solenoid and this switch comprises in its preferred form an arcuate tubular body constructed of any suitable insulating material;

The arcuate tubular switch body 59 has a movable circuit closing medium such as a slug of mercury indicated-at therein. This movable liquid circuit closer 60 is adapted to bridge any one of. the plurality of sets or pairs of spaced contacts carried by the body 59. The pairs of contacts are spaced along the length of'the arcuate tubular body 59.

The spaced pair of contacts 6| and the spaced 'pair 64 are positioned at the ends of the arcuate tubular body 59, while the pairs 62 and 63. and 60' are spaced at predetermined intervals along the tube and extend into pockets adapted to receive the slug of liquid 60 for bridging the contacts of the respective pairs.

One of thecontacts of each pair of contacts is connected through a suitable connector 66 with a line wire 61 of the supply line of electrical current to the apparatus. The other contacts of each of the pairs of contacts are'connected by suitable wiring with the respective coils of the solenoid 50, for example, one of the contacts of the pair of contacts 68' is connected to the coil 53 through the medium of the wire 68. One of the contacts of the pair of contacts 62 is connected by the wire 69 to the coil 54, while the proper contacts of the pairs of contacts 63, 64 and 6| are-connected by wires 18, 1| and 12 with the coils 55, 56 and 51 respectively of the solenoid 50.

The various coils of the solenoid 50 are connected to 'the wire 13 of the electric current supply line by suitable wires so that when any pair of the contacts are bridged by the liquid circuit closer 68, a corresponding coil of the solenoid 5|] will be energized for drawing the core 5| thereinto and moving the valve piston 2| correspondingly. Visible signals 19 are connected in the circuit with the solenoid coils and they are operated upon the energizing of the coils so that the particular coil energized may be readily determined and consequently the loaded or unloadthe lever 83 is raised upon pressure increase and lowered through the medium of the weight 86 by pressure decrease. The pressure fluid entering the pressure operated structure through the pipe 84 is preferably pressln'e fluid from the receiver (not shown) into which the compressor structure discharges.

In operation; when the pressure in the receiver (not shown) reaches a predetermined degree, the lever 83 will be moved and move the rack 82, which in turn will rock the arcuate tubular body 59 into such position that the liquid circuit closer 60 will bridge the contacts of the pair of contacts 68., which will close the circuit through the coil 53 of the solenoid 58 and move the core 5| one step or suflicient distance to open the fluid inlet 2| to the port 22. Fluid under any desired pressure is delivered into the distributor valve cylinder through the port .2|', so that when the piston 2| is moved by the energizing of the coil 53 of the solenoid, this fluid under pressure will pass through the port 22 and pipe 23, into the cylinder 24 of the intermediate valve structure 25 and through the cylinder 24 and pipe 26 into the cylinder I! of the pressure operated unloading device Said pressure fluid entering the cylinder |1 inwardly of the piston l6 will force the piston l6 outwardly and unseat the valve disc I4. This opens the crank end 3 of the cylinder I to the clearance.

arcuate tubular body 59 will be moved or rocked so as to bring the liquid contact closing medium 68 into the pocket 65 for bridging the contacts of the pair 62. This will energize the coil 54 of the solenoid 50 and move the valve piston 2| a further step, opening the port 2| to the port 21. The fluid under pressure passes from the port 21 through the pipe 28 into the enlarged portion 29 of the cylinder 24 and acts on the piston 30 of the intermediate valve structure, 25. Owing to the increased area of the piston 30 over the piston sec-* tions 3| and 32 of the valve 25, this pressure fluid will move the plunger comprising the pistons 30, 3| and 32 so as to cut off communication between the pipes 23 and 26 and permit the fluid under pressure, which is in the cylinder IT to bleed therefrom through the exhaust pipe 34 of the intermediate valve structure 25. The port 2! alsohas a pipe 35 connected thereto so that at ,the same time, that the pressure fluid is admitted into the enlarged portion 29, the fluid will be admitted to the cylinder ll of the unloading mechanism I2 in back of the piston l6 thereof and move the piston to unseat the valve disc M for opening the head end 4 of the cylinder to the clearance chamber 6. The capacity of the clearance chamber 6 is such that this operation wh'olly unloads the'head end of the cylinder and permits the compressor to operate at 50% of its full capacity since when the pressure fluid is permitted to exhaust from the cylinder ll of the unloading mechanism The pressure back of the piston thereof will seat the valve disc l4 and cut of! communication between the crank end 3 of the cylinder and the clearance chamber 1.

Upon further increase of receiver pressure, the tubular switch body 53 is further moved so as to shift the liquid circuit closer 60 into engagement with the contacts of the pair 63, which energizes the coil 55 of the solenoid 50. The energizing of the coil 55 of the solenoid 50 moves the valve piston 2| an additional step to the right, which brings the port 35' into communication with the port 2| and permits the pressure fluid to enter the enlarged portion 29 of the cylinder 24 in front of the piston 30. Owing to the increased area of the outer side of the piston 30 over its inner side, the pressure fluid acting thereon together with the pressure applied by the spring 35, will force the plunger 33, which comprises the pistons 30, 3| and 32 to the left, in the drawing, and again open communication between the pipes 23 and 26.to permit pressure fluid to be admitted to the cylinder H of the unloading device H in front of the piston l6 thereof to unseat the valve disc l4 and again open the crank end 3 of the cylinder to the clearance chamber 1, providing a reversed step in the unloading operation of the compressor. At this time, the valve disc H of the unloading mechanism |2 will be held unseated through admittance of pressure fluid to the unloading mechanism through the pipe 35 and thus the head end 4 of the cylinder I will be wholly unseated and the crank end 3 will be unloaded 50%, which will permit the compressor to operate at 25% of its capacity.

Upon a further increase of receiver pressure, the tubular body 59 will be further rocked to bring the liquid circuit closer medium 60 into bridging engagement with the contacts of the pair 54, which will energize the coil 56 of the solenoid 50 and move the valve piston 2| to its furthermost limit to the right and open the port 31 to receive fluid under pressure from the port 2 The fluid under pressure passing through the port 31 will enter the cylinder ll of the unloading mechanism I3 and move the piston l6 thereof to unseat its corresponding valve disc H, which opens the head end 4 of the cylinder through the clearance chamber 6 and clearance chamber 1 to the crank end 3 of the cylinder and permits the by-passing of the fluid compressed by the reciprocation of the piston 2 and consequently wholly unloads both ends of the cylinder and permits the compressor to operate at zero capacity.

Decrease in receiver pressure reverses the operation above described, the compressor being loaded in a graduated manner in the same portion as that in which it is unloaded; i. e., upon decrease in receiver pressure the pressure is relieved in the mechanism 85 and the lever allowed to rock the tubular body 59 in a reverse direction and deenergize the coil 56 and energizes the coil 55 of the solenoid 5|! for moving the valve piston 2| in a reverse direction, or to the left, one step which will cut-off the port 31 from the port 2|, relieving the pressure in back of the piston I6 of the unloading mechanism |3 to permit the pressure fluid to bleed from the cylinder I! out through the exhaust 34 and allow the valve 4 to be seated by the pressure of the spring 8 and pressure fluid in front of the piston l6 through the pipe 40, thus cutting off the by-pass communication between the head end 4 and crank end 3 of the compressor and causes the compressor to operate at 25% of its maximum capacity.

The various steps heretofore described, are repeated in a reverse direction until the compressor is operating at 75% of its capacity and then upon a further decrease in receiver pressure, the tubular body 59 is rocked to its furtherest limit to the right and the lower end of the liquid circuit closing medium 60 is brought into bridging engagement consequently, the compressor operates at full or 100% capacity.

It will be understood that the invention is not to be limited to the specific construction or arrangement of parts shown but that they may be widely modified within the invention defined by the claims. 4

What is claimed is:

1. In combination, a distributor valve including a cylinder having a plurality of pressure fluid ports for selectively delivering pressure fluid, a piston controlling said ports, a plurality of independent solenoid coils, a solenoid core connected to said piston whereby energizing of the respective solenoid coils will move said piston in corresponding port controlling positions.

2. In combination, a distributor valve including a cylinder having a plurality of pressure fluid ports for selectively delivering pressure fluid, a piston controlling said ports, a plurality of independent solenoid coils, a solenoid core connected to said piston whereby energizing of the respective solenoid coils will move said pis-' ton in corresponding port controlling positions, a selective switch controlling energizing of said solenoid coils, and means operated by pressure of fluid compressed for operating said selective switch. v

3. In combination, a distributor valve including a cylinder having a plurality of pressure fluid ports for selectively delivering pressure fluid, a piston controlling said ports, a plurality of independent solenoid coils, a solenoid core connected to said piston whereby energizing of the respective solenoid coils will move said piston in corresponding port controlling positions, a mercury tube switch selectively controlling energizing of said solenoid coils, and pressure operated means for operating said selective switch.

4. In combination, a distributor valve including a cylinder having a plurality of pressure fluid ports for selectively delivering pressure fluid, a piston controlling said ports, a plurality of independent solenoid coils, a solenoid core connected to said piston whereby energizing of the respective solenoid coils will move said piston in corresponding port controlling positions, and means whereby said coils may be energized in succession or in irregular sequence.

5. In combination, a distributor valve includ-- ing a cylinder having a plurality of pressure fluid ports for selectively delivering pressure fluid, a piston controlling said ports, electrical means for moving said piston in port controlling positions, and a selective switch controlling energizing of said electrical means.

6. In combination. a distributor valve includ ing a cylinder having a plurality of pressure fluid ports for selectively delivering pressure fluid, a piston controlling said ports, electrical means for moving said piston in port controlling positions, and a selective switch controlling energizing of said electrical means, and pressure operated means for operating said selective switch.

7. In combination, a distributor valve including a cylinder having a plurality of pressure fluid ports for selectively delivering pressure fluid, a

piston controlling said ports, a plurality of inde- I pendent solenoid coils, a solenoid coil connected to said piston whereby energizing of the respective solenoid coils will move said piston in corresponding port controlling positions, a. selective switch energizing of said solenoid coils and means for operating said selective switch whereby said coils may be energized in succession or irregular sequence.

WALTER W. SCI-IROEDER. 10 

